Sewage Irrigation Area Of Tianjin Beijing Heavy Metals In The Soil Of The Spatial Distribution And Influencing Factors Of Research

Taking Farmland soil of Tianjin located in the Beijing sewage irrigation area as the research object, did soil digestion by using microwave digestion method, and using inductively coupled plasma mass spectrometer (ICP-MS) measured the heavy metals(Cr, Ni and Cu Zn, Cd and Pb) total amount of sampling sites, and analyzed its distribution characteristics, the results showed that: The average value of Cr is73.529, the average value of Ni is49.094, the average value of Cu is30.161, the average value of Zn is121.85, the average value of Cd is0.278, the average value of Pb is32.142, which average values of Ni, Zn, Cd is more than the soil environmental second level in Tianjin, the most serious is Cd. It can be seen that by the correlation analysis between the total amount of all heavy metals, except for Cr-Zn and Cr-Cd, the rest of the heavy metal elements showed a significant or very significant level (positive correlation), indicating that homologous is very high between the elements. Derived through analyzing the correlation between the total amount and physicochemical properties of heavy metals that between each heavy metal and their physicochemical properties (water content, PH, salinity, organic matter) showed varying degrees of correlation.To do environmental quality assessment with the sampling sites soil, from the evaluation results of the single-factor pollution index, Cd is the most prominent, and the average of the single pollution index reached1.746; from the evaluation results of the comprehensive pollution index, number S28in fifth heavily polluted level, S2, S4, S19, S10, S18in fourth moderately polluted levsl, in addition, other sampling points belong to the light pollution or still clean level.Morphological analysis of heavy metals was taken by Tessier sequential extraction, results showed that heavy metals in each form there are some differences in the proportion of its total, but overall the residual state is dominant, the carbonate-bound state and the effective state of heavy metals in the lowest levels except Cd and Cu. And through the analysis, the relationship between the total amount of heavy metals and their effective states was significant except Cu. The correlation analysis of heavy metals morphology and soil physical and chemical properties shows that: the carbonate-bound state and organic-bound state of Ni, Fe-Mn oxidation state of Cu, organic-bound state of Cd showed a significantly positive correlation with soil moisture. Effective state of Cr and PH was significantly negatively correlated, while the other form showed a very significantly positive correlation with PH, Fe-Mn oxidation state and organic-bound state of Ni, organic-bound state of Cu and PH were in a significantly positive correlation, while the carbonate-bound state of Zn and Cd were significantly negatively correlated with PH; Fe-Mn oxidation state and organic-bound state of Cr, effective state of Ni, effective state and organic-bound state of Cu showed a significantly positive correlation with soil salinity; organic-bound state of Cr, Fe-Mn oxidation state of Cd, carbonate-bound state and organic-bound state of Cu were significantly positively related with soil organic matter, effective state of Ni, Fe-Mn oxidation state of Cu were significantly negatively related with soil organic matter.Analysis of soil salinization process on heavy metals were found to influence, soil heavy metals (Cr, Ni, Cu, Zn, Cd) in various forms and soil inorganic anion and cation showed a degree of correlation, and some significant or extremely significant level, in addition to Ca2+and Mg2+Na+, K+more speciation of heavy metals and the correlation between the performance of more positive, this may be because the Ca+and Mg+in soil with heavy metal ions adsorption sites and foreign competition, also can reduce soil PH, make more H+and competitive adsorption of heavy metals sites. And soil inorganic salt anions (CO32-, HCO3-, SO42-, CL-)and soil heavy metals correlation show certain differences, this may be because the inorganic salt anion adsorption of heavy metals by soil type and cationic varies, and the soil CO32-often increases in soil heavy metal’s carbonate state content increased.